This paper reviews recent progress of high-power 14xx-nm pump lasers using AlGaInAs/InP material. This material has superior temperature characteristics to conventional InGaAsP/InP. As a result, it is more suitable for high current and high efficiency operations as well as uncooled applications for the high power 14xx-nm lasers, which are required for advanced optical amplifications. The laser module consists of a laser chip coupled to a fiber lens and mounted on a thermoelectric cooler in a standard butterfly package. The wavelength of the laser can be stabilized with an external fiber Bragg grating (FBG). We have demonstrated a maximum module fiber output power of 550mW at 1.75A and characteristic temperatures of T0 = 99K and T1 = 348K over a range of chip heat-sink temperatures from 15°C to 50°C. To the best of our knowledge, these are the highest efficiency and temperature characteristics from a single-mode 14xx-nm semiconductor laser module capable of over 0.5W fiber output power. At a chip heat-sink temperature of 70°C, a power of 360mW was obtained for a laser module with FBG, which is the highest reported to date for any wavelengths from 1300nm to 1600nm and would enable uncooled applications of the 14xx-nm lasers in the future.
We present the theoretical foundations and implementation methods for forming GaAs compliant substrates that have a 'stretchable' lattice to be used for high quality lattice- mismatched heteroepitaxial growth. The theoretical calculations predict an increase of several orders of magnitude in the critical thickness of a film when it is grown on another thin film that has been wafer-bonded to an angularly misaligned bulk substrate. The calculations show that the increase in critical thickness is sustained even for a 3 percent lattice mismatch between the growth and the stretchable lattice. The dependence of the growth's critical thickness on a variety of parameters are presented including the bonding energy between the compliant and bulk substrates, the lattice mismatch between the growth and compliant substrates, and the thickness of the misaligned film. Thick films of In0.35Ga0.65P were grown on the compliant substrates. Bright-field transmission electron micrographs of the growth's cross-section showed no dislocations, whereas the same films grown on bare GaAs substrates produced stacking faults and threading dislocations. The concept and technology of compliant substrates may have important applications in forming optoelectronic devices of new characteristics and wavelengths.
Wafer-bonded AlAs/GaAs mirrors and AlGaInAs strain- compensated multiple quantum well active layers have been applied into 1.3 micrometer vertical-cavity surface-emitting lasers (VCSELs). Double-bonded 1.3 micrometer VCSELs have operated at room temperature pulsed conditions with a high output power of 4.6 mW, a high characteristic temperature of 132 K, and a large side-mode suppression-ratio of 42 dB. A novel more practical approach for 1.3 micrometer VCSELs have been proposed and demonstrated a very low room temperature pulsed threshold current density of 1.13 kA/cm2 and a very low threshold current of 2 mA. Further improvement focusing on practical approaches for long wavelength VCSELs is underway.
This paper describes the wafer bonding technology and its applications to optoelectronic devices and circuits. It shows that the wafer bonding technology can create new device structures with unique characteristics and can form integrated optoelectronic circuits containing optical, electronic and micro-mechanical devices.